Treatment of monocyclic olefinic hydrocarbons



Patented May ZO, i947 OF MONOCYCLIC OLEFINIC Vladimir N. Ipatiefl and Universal 111., assignors to HYDROCARBQNS I Herman Pinon Chicago,

Oil Products Company, Chicago, 111., a corporation of Delaware No Drawing. Application April 28, 1945, a Serial No. 590,959

This invention relates to a ing. monocyclic olefinic hydrocarbons into substantial yields of aromatichydr'ocarbons. More particularly, the process relates to the production of alkyl aromatic hydrocarbons process for convertby the" action "of particular catalysts upon monocyclic terpenic hydrocarbons.

An object of this invention is to convert unsaturated cyclic hydrocarbons into a substantial yield of aromatic hydrocarbons.

A further object of this invention is to produce cymeneand methyl isopropyl cyclohexene by reacting limonene in the presence of a. selected acid-acting catalyst.

One specific embodiment of the present invention relates to a process which comprises reacting a monocyclic olefinic hydrocarbon containing two double bonds per molecule at a temperature of from about 100 to about 400 C. in the presence of a dilute aqueous solution of an acid-acting catalyst. I

We have found that hydrogen disproportionation or a transfer occurs when a hydrocarbon selected from the group consisting of a monocyclic terpene and a monocyclic diolefinic hydrocarbon is reacted in the presence of an acidacting catalyst and particularly a relatively dilute aqueous solution of said acid-acting compound. Thus we observed that limonene when treated with a dilute aqueous solution of magnesium chloride gave substantial yields of p-cymene and dihydrolimonene. This treatment of limonene with magnesium chloride solution caused substantially no polymerization but caused the formation of substantial amounts of the aforementioned p-cymene and dihydrolim'onene. Accordingly, the reaction which occurred may be expressed by the following equation:

v( 3H. on.

Catalyst one-(hon, (Ell-CH; CHz-CH-CH; Dihydrolimonene vention are preferably those I intention of limiting unduly catalysts after use in ydrocarbonconversion reactions such as alkylation and polymerization. The reaction forming aromatic hydrocarbons also proceeds more easily with cyclic olefins and monocyclic terpenes in I which the cyclic ring contains six carbon atoms, I I

Catalysts utilizable in the process of our in which do not have pronounced polymerizing properties and comprise essentially an aqueous solution of an acid-acting inorganic compound. The catalysts which we recommend for this reaction are aqueous solutions of acid-acting salts such as ferric chloride, magnesium chloride, aluminum chloride, zinc chloride, sodium acid sulfate, etc., and also dilute aqueous solutions of certain oxygen-containing mineral acids, particularly phosphoric acid and other acids of phosphorus. In general, the catalyst solution utilized in our process contains from about 0.1 to about5% by weight of the acidacting salt or mineral acid. The pH of the aqueous solution used as catalyst is preferably less than 4. The type of catalyst to be used depends greatly upon the nature of the compound or compounds submitted to a hydrogen transfer reaction.

The process of this invention is carried out using either batch or. continuous operation. When the treatment of the unsaturated'hydrocarbon with the catalyst is effected continuously, the used catalyst solution is recovered and recycled to further contact with the hydrocarbon or hydrocarbon mixture being treated. The

hydrogen transfer and converting terpenic hydrocarbons into aromatic hydrocarbons but we preferto use a temperature of from about to about 350 C. for efficient conversion into aromatic hydrocarbons.

The following example is given to illustrate the process of the invention, although with no its generally broad scope. I

One molecular proportion of limonene and 5.5 molecular propo' ions of water containing 0.03 mole of magnesium chloride dissolved therein were placed in an autoclave and heated at 300 C. for 3 hours. During this treatment 20% by weight of the d-limonene was converted into p-cymene.

The foregoing specification and example indicate the character of this process although with 3 4 no intention or unduly limiting the broad scope 5. A process for producing an aromatic hydrootthe invention. carbon which comprises reacting a monocyclic diwe claim as our invention: oieiinlc hydrocarbon containing a ring of 6 car- 1. A process for producing an aromatic hydrobon atoms in the presence of a dilute aqueous carbon which comprises reacting a monocyclic l loiution containing from about 0.1 to about 5% dioleflnic hydrocarbon containing a ring oi 6 by weight oi an acid-acting catalyst at a temcarbon atoms in the presence of a dilute aqueous perature or from about 150' to about 350' 0. solution containing from about 0.1 to about 5% 8. A process tor producing an aromatic hydroby weight an acid-actingcatalyst at a temcarbon which comprises reacting a monocyclic perature oi from about 100' to about 400' 0. l0 erpenic hydrocarbon in the presence 01 a dilute 2; A proces jor producing an aromatic hydroaqueous solution containing from about 0.1. to

' carbon which comprises reacting a monocyclic about by weight ot an acid-acting catalyst at terpenic hydrocarbon inthe presenc or a dilute a'temperature oi irom about 150' to about 350' 0. aqueous solution containing from about 0.1 to VLADIMIR N. IPATIEFF. 52123. i' fi fm tfi tifit mm at a t 0! rom a u a um .nmmcns crrnn 8. A process for prod cing P-cymene which The m m rm-ences f comprises reacting limonene at a emperature or me or this Mint: are 0 record in the from about 150' to about 850' C. in the presence r m mucou oluflon mntainmg from m 0.1 Chem. Ah. V0]. 27, (Ptto about 5% by weight or an acid-acting ca alyst. LIM

4 A for produ in p cmene et 31 Join. Am- Chem. 8C., V01. 66, comprises reactin llmonene at a temperature of 1120-2 Pat-011mb) from about 150- to about 350' o. in the presence mm et Chem- 1-. 0! an aqueus solution containing from about 0.1 (PW 141,-) to about 5% by weight of m gnesium chloride. 

